Likelihood ratio test for mkinfit models

- - -

Compare two mkinfit models based on their likelihood. If two fitted -mkinfit objects are given as arguments, it is checked if they have been -fitted to the same data. It is the responsibility of the user to make sure -that the models are nested, i.e. one of them has less degrees of freedom -and can be expressed by fixing the parameters of the other.

- -

# S3 method for mkinfit
-lrtest(object, object_2 = NULL, ...)
-
-# S3 method for mmkin
-lrtest(object, ...)

- -

Arguments

object: An mkinfit object, or an mmkin column -object containing two fits to the same data.
object_2: Optionally, another mkinfit object fitted to the same data.
...: Argument to mkinfit, passed to -update.mkinfit for creating the alternative fitted object.

Details

Alternatively, an argument to mkinfit can be given which is then passed -to update.mkinfit to obtain the alternative model.

The comparison is then made by the lrtest.default -method from the lmtest package. The model with the higher number of fitted -parameters (alternative hypothesis) is listed first, then the model with the -lower number of fitted parameters (null hypothesis).

- -

Examples

# \dontrun{
-test_data <- subset(synthetic_data_for_UBA_2014[[12]]$data, name == "parent")
-sfo_fit <- mkinfit("SFO", test_data, quiet = TRUE)
-dfop_fit <- mkinfit("DFOP", test_data, quiet = TRUE)
-lrtest(dfop_fit, sfo_fit)
-#> Likelihood ratio test
-#> 
-#> Model 1: DFOP with error model const
-#> Model 2: SFO with error model const
-#>   #Df  LogLik Df  Chisq Pr(>Chisq)    
-#> 1   5 -42.453                         
-#> 2   3 -63.954 -2 43.002  4.594e-10 ***
-#> ---
-#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
-lrtest(sfo_fit, dfop_fit)
-#> Likelihood ratio test
-#> 
-#> Model 1: DFOP with error model const
-#> Model 2: SFO with error model const
-#>   #Df  LogLik Df  Chisq Pr(>Chisq)    
-#> 1   5 -42.453                         
-#> 2   3 -63.954 -2 43.002  4.594e-10 ***
-#> ---
-#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
-
-# The following two examples are commented out as they fail during
-# generation of the static help pages by pkgdown
-#lrtest(dfop_fit, error_model = "tc")
-#lrtest(dfop_fit, fixed_parms = c(k2 = 0))
-
-# However, this equivalent syntax also works for static help pages
-lrtest(dfop_fit, update(dfop_fit, error_model = "tc"))
-#> Likelihood ratio test
-#> 
-#> Model 1: DFOP with error model tc
-#> Model 2: DFOP with error model const
-#>   #Df  LogLik Df  Chisq Pr(>Chisq)    
-#> 1   6 -34.587                         
-#> 2   5 -42.453 -1 15.731  7.302e-05 ***
-#> ---
-#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
-lrtest(dfop_fit, update(dfop_fit, fixed_parms = c(k2 = 0)))
-#> Likelihood ratio test
-#> 
-#> Model 1: DFOP with error model const
-#> Model 2: DFOP with error model const and fixed parameter(s) k2
-#>   #Df  LogLik Df  Chisq Pr(>Chisq)    
-#> 1   5 -42.453                         
-#> 2   4 -57.340 -1 29.776  4.851e-08 ***
-#> ---
-#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
-# }
-

- -